This invention is concerned with improvements in or relating to a roof tile and particularly this invention is concerned with improvements in or relating to contoured interlocking roof tiles.
By "contoured" where used herein it is meant a roof tile having a profiled upper surface, for example, a double Roman, a bold roll or similar tile. Such a tile generally comprises profiled side portions on each side of a profiled central portion with the side portions being provided with upwardly or downwardly facing channels respectively for facilitating, in use, the interlocking of each tile with sideways adjacent tiles on a roof.
It is well known that the front edge thickness of most interlocking concrete roof tiles is governed by the minimum thickness required for the interlock at the longitudinal edges of the tiles. The thickness of the interlock portion of the tile is maintained across the tile so that the depth of a front edge surface thereof, i.e. that surface facing downwardly of a roof, in use, is constant or substantially so. Thus, when one tile is laid upon another in use, no gaps are evident between the overlapped head and tail lap portions of the tile whether the tiles are laid in full bond or broken bond relationship across the roof. When the roof tiles are placed on a roof, the edge surfaces of the tiles extend at a right angle to the slope of the roof. Horizontal rows of the tiles overlap adjacent rows of the tiles leaving the front edge surface with respect to the position of a tile on the roof visible to a person looking up at the roof. This front edge surface is thus considered to face downwardly of a roof in use.
Such design of roof tile dictates that an unnecessary proportion of the tile weight is evident in the thick front edge portion of the tile which thick front edge portion adds little if any structural value to the tile and has a principal aim of closing any gaps which might otherwise be evident between overlapped tail and headlap portions of tiles laid on a roof.
The present invention seeks to mitigate or overcome the shortcomings of known tiles and involves a roof tile with a profiled upper surface and a front edge surface, which front edge surface extends across the width of the tile and faces downwardly of a roof in use, wherein the front edge surface is of progressively greater depth as between a relatively thin profiled central portion and thicker profiled side portions thereof.
Prior art document FR-A-1097530 describes tiles having a front edge surface which is progressively greater depth as between a relatively thin profiled central portion and thicker profiled side portions. However, this prior art document describes tiles which can only be laid in full bond relationship. Prior art document DE-C-16814 describes tiles with a thickness in cross-section which varies across their width; however, these tiles do not have a profiled upper surface. Neither of these prior art documents disclose the features of the present invention.